1. Field of the Invention
This invention relates to injector nozzles and more particularly relates to preventing the obstruction of injector nozzles.
2. Description of the Related Art
Injector nozzles are often used in contaminated environments. For example, injector nozzles used in exhaust after treatment systems are often in contact with exhaust, and other contaminants. Dosing systems with injector nozzles are useful in these environments, because they can inject fuels, reducing agents such as urea (also known as carbamide) or ammonia, or other dosing fluids into an exhaust stream for regeneration or oxidation of system components, or reduction of exhaust emissions such as nitrogen oxides. Dosing systems are used with diesel engines, boilers, power plants, and other applications that produce exhaust.
Injecting fuels, catalysts, or reductants into an exhaust stream can burn or oxidize soot and other contaminants that have collected in filters or other exhaust system components, or reduce exhaust emissions. Examples of exhaust system components that may benefit from dosing include catalytic converters, such as diesel oxidation catalysts (DOCs), selective catalytic reduction (SCR) systems, selective non-catalytic reduction (SNCR) systems, and filters such as soot traps and diesel particulate filters (DPFs).
Soot and contaminants from exhaust also attach to the injector nozzles that are used in dosing systems, an effect called carboning. Injector nozzles are especially prone to carboning while they are wet after dosing. Carboning can affect the spray formation and the spray volume of an injector nozzle. The buildup of soot and contaminants on an injector nozzle has many detrimental effects on dosing, including decreased regeneration or reduction performance and decreased fuel economy or emission reduction. In extreme cases, exhaust system components may become completely plugged with soot and other contaminants, causing uncontrolled dosing and damage to the exhaust system components.